The present invention relates to an anti-friction device, such as, for example, a ring, associated with a drilling element, such as, for example, a drill pipe, a tool joint, or a sub. The device of the present invention is adapted to reduce the sliding, rolling or mixed friction between the drilling element and the walls of the open borehole or the walls of casings during the operating steps.
It is known that, during the drilling operations, said drilling elements generate friction against the borehole walls, especially when drilling wells requiring the use of water-based muds, as opposed to oil-based ones. This problem is particularly felt when drilling deep or extended reach wells.
It is known that, as friction increases, more torque is required from the top drive or rotary table for drilling to be carried out correctly.
According to the latest drilling rig technology, the top drive is preferred over the rotary table for applying drilling torque.
The use of the top drive, due to its very shape, considerably speeds up the steps of inserting and extracting the pipes. Such devices can only withstand a maximum torque value. Should said maximum torque be exceeded, damage may occur to the device itself as well as to the drill pipes.
The friction generated by said drilling elements further increases when drilling deep, deviated or horizontal wells, also known as extended reach wells, where the well target may be offset by more than ten kilometers from the well head.
Systems known in the art try to solve this problem in a passive way by using oil-based drilling muds, which however are being dismissed for environmental reasons, or by having the top drive cooperate with well bottom engines in order to obtain the required torque. The latter solution is not sometimes resolutory, particularly when extended reach wells are involved, and makes for higher running costs.